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Allergic versus Contagious Conjunctivitis: Do You Know the Difference? 

Feb 22, 2024

5 min read

Is it contagious? Do I need to quarantine? We got all your questions answered by a healthcare professional.

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A woman rubbing her eyes due to irritation.
Saloni Prajapati - Fluent Health



Tired of dealing with red, itchy eyes? The kind that look suspiciously ‘pink’ and warrant that dreaded ‘quarantine’? Is it conjunctivitis? Before you panic about screen time (yes, you should reduce that anyway), there are two main suspects: Allergic conjunctivitis and contagious conjunctivitis. While both cause redness and discomfort, knowing the difference is crucial for seeking the right treatment and preventing the spread of infection.

Eye discomfort, characterised by redness, itching, or excessive tearing, is a common concern for various reasons. Two prevalent reasons are contagious conjunctivitis, caused by viral bacterial infections, and allergic conjunctivitis, triggered by exposure to allergens. The good news? The latter isn’t as contagious as you think.

What is Conjunctivitis?

Conjunctivitis, or pink eye, is an inflammation of the eye’s thin, protective membrane called the conjunctiva. It can result from infections, allergies, or irritants, causing redness, itching, tearing, and discharge. 

Conjunctivitis didn’t just pop out of the blue in modern times. Our obsession with kohl isn’t just for the sake of vanity. Kohl or kajal is traditionally believed to be ‘medicinal’ in nature. It was originally made by grinding stibnite (a sulfide mineral) or galena (lead sulfide). The lead properties might have actually staved off an eye infection or two. However, there is, and was always, the more dangerous risk of lead poisoning. But seeing that doctors were scarce (read non-existent ) in ancient times, kajal gained the reputation of being more than just protection against the evil eye.   

Some experts even believe that in ancient Egypt, when the Nile flooded, Egyptians suffered from infections caused by particles that entered the eye. Their lead-based make-up acted as a barrier, killing bacteria before it spread. 

What is the significant difference between contagious and allergic conjunctivitis?

Contagious conjunctivitis:

 It’s caused by viruses or bacteria that can spread via contact with infected eyes, hands, or contaminated objects like handkerchiefs, towels, shared eye makeup. Symptoms typically appear suddenly and may include itchy or burning eyes, redness, excessive tearing, pus discharge, and crusting around the eyelashes. 

Allergic conjunctivitis:

Triggered by an allergic reaction to pollen, dust mites, pet dander, or other allergens and usually affects both eyes. Is allergic conjunctivitis or allergic pink eye contagious? No, but symptoms often occur seasonally or when exposed to the allergen. They may include itchy, watery eyes, redness, and swollen eyelids. 

The key factors to consider are as follows: 

Table explaining difference between contagious and allergic conjunctivitis.

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To get up close and personal, we spoke to ophthalmologist Dr Mandeep Singh Basu, based in Basu Eye Hospital, in New Delhi.

Q: Are there any specific tests to determine whether the conjunctivitis is allergic or contagious?

Dr Basu: It takes a professional evaluation to determine whether it’s allergic or contagious. Exposure to allergens causes allergic conjunctivitis, while infectious forms, bacterial or viral, spread by contact. To get a precise diagnosis, speak to an eye care specialist. To determine the cause of an allergy, allergy tests, symptom analysis, and medical history evaluations are helpful. Bacterial or viral cultures may be required for contagious conjunctivitis. Timely consultation guarantees the right course of action, be it antibiotics for infectious illnesses or antihistamines for allergies. Self-diagnosis can result in inefficient and incorrect treatment. 

Q: How long do symptoms last, and when should people seek immediate medical attention?

Dr Basu: It depends on the cause. Conjunctivitis symptoms last for different periods. As long as the allergen exposure occurs, allergic conjunctivitis may recur, although bacterial or viral infections usually clear up in one to two weeks with appropriate care. It is essential to seek medical assistance if symptoms worsen or continue after this period. If you experience severe eye pain, changes in your vision, extreme redness, or light sensitivity, you should get medical attention immediately. These symptoms could indicate a more severe issue or complications, suggesting immediate care to avoid potential blindness. Regular follow-ups can ensure appropriate management and healing.

Q: Are there lifestyle changes I can adopt to reduce the likelihood of recurrence? 

Dr Basu: Work closely with your healthcare expert to identify specific allergens triggering your reactions. Avoid touching your eyes too often. Be cautious of the quality of eye makeup used and avoid sharing eye products. Allergen-proof your home with covers on pillows and mattresses; keep your living space clean; and consider using air purifiers. When outside, think about wearing shades to protect your eyes from airborne irritants. Limit exposure to pet dander if it triggers you, or make sure your pet is well-groomed. Adherence to prescribed allergy medications, regular check-ups with healthcare providers, and staying informed about allergy management strategies contribute to a comprehensive approach to reducing the recurrence of allergic reactions. 

Medically Reviewed By:

Dr. Sujata Chakravarti, Family Physician

Saloni Prajapati - Fluent Health

Saloni Prajapati started in entertainment journalism at India TV before seamlessly venturing into the world of AI, tech, and start-ups. Known for her insightful reporting, she likes to tell stories about the industry in a way that’s meaningful for her viewers and readers.

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